Slow thunder underground.

A tiger worm tunnels through the Bywater's compost heap, eating everything before it.

In the tiger worm's gut acids, enzymes and bacteria break down the compost to extract energy and nutrients. Then the smooth muscles round its gut contract in a rippling wave and the undigested minerals (puffed up with bacteria and moisture) are squeezed out behind.

More humus for the Bywater's organic vegetable garden.